The Pay Equity Amendment Bill passed on Wednesday after being rushed through Parliament under urgency.
Affected workers say they are "angry", "hurt" and "disappointed" and feel betrayed by the architect of the legislation, Workplace Relations and Safety Minister Brooke van Velden, but are determined to keep fighting.
The legislation means 33 equity claims being negotiated will now have to restart the process under new criteria.
Nationwide protests took place yesterday.
In Dunedin, members from unions across a variety of sectors including First Union, the New Zealand Nurses Organisation and the Public Service Association gathered in the Exchange to stand in solidarity against the amendment to the Equal Pay Act.
PSA organiser Jen Wilson said the rally was a fairly spontaneous uprising of anger and disgust by women and people who cared about women.
She could not believe the Pay Equity Amendment Bill was passed on Wednesday.
"I was shocked."
The changes were not about equity and were about making cuts for the Budget, she argued.
Although the process was not perfect it had been delivering pay increases and gender fair pay to women over the past few years.
"For some claimants it will be impossible to make a payment successfully.
The consequences of the amendment to the Bill were ultimately poverty and hardship.
A petition had gathered more than 56,000 signatures to reverse all claim cancellations, undo equal pay act changes and deliver pay equity.
Earlier this week, Ms van Velden said pay equity claims had been able to progress without strong evidence of undervaluation and it was difficult to tell wether the difference in pay was due to sex-based discrimination or other factors.
Claims had cost the Crown $1.78 billion a year and the changes to discontinue current pay equity claims significantly reduced costs to the Crown.
The current Act was not working as intended and a new and improved pay equity system would provide greater confidence that genuine pay equity issues would be correctly identified and addressed, she said.
